1. Technical Field of the Invention
The present invention relates to a vehicle frame joint and to a vehicle frame for a saddle-type vehicle, such as a motorcycle or the like.
2. Background Art
Heretofore, vehicle frame structures for saddle-type vehicles, including main frames with subframe portions bolted in a detachably mounted manner thereto, have been known (see, for example, Patent Documents 1 through 3 below). When positioning a joint between the main frame and the subframe, such as within a longitudinally intermediate portion of a continuously extending frame component, it is customary, as described in Patent Document 1, to longitudinally split the portion of the frame component at the joint into adjacent joint arms. The joint arms may be fastened together while being held in abutment against each other in the longitudinal direction. The following references provide further background: Japanese Patent Laid-open No. Sho 59-160679 (“Patent Document 1”); Japanese Utility Model Publication No. Hei 3-3119 (“Patent Document 2”); and Japanese Utility Model Laid-open No. Sho 59-133386 (“Patent Document 3”).
However, the structures of the background art tend to concentrate stresses on the boundary between general cross-sectional portions of the frame component and the split joint arms, which adversely affects the rigidity of the frame component and correspondingly the rigidity of the vehicle frame. While the joint may be increased in size to keep the desired frame rigidity, the necessary corresponding enlargement of the frame component tends to adversely affect the design of the vehicle body.
Although the known frame structures have some utility for their intended purposes, a need still exists in the art for an improved frame structure. In particular, there is a need for an improved frame structure which will improve over the known frame structures.